Re: CMD23 plumbing and support patchset.

[Andrei Warkentin <andreiw@motorola.com>]

On Fri, Apr 22, 2011 at 9:51 PM, Chris Ball <cjb@laptop.org> wrote:
> Hi,
>
> On Thu, Apr 21 2011, Andrei Warkentin wrote:
>>>> Can you give me the manufacturing date? This is pretty interesting.
>>>>
>>>> You can see an improvement even if you do something like time block
>>>> writes (O_DIRECT | O_SYNC, of course). But after all synthetic tests I
>>>> measured the time it took to do 40000 SQLite insertions and saw
>>>> something like 30% improvement.
>>>>
>>>
>>> And you're trying this on SDHCI I presume, right?
>>
>> Is this on the same board as the other log you sent? Controller is
>> SDHCI-PXA? If you give me  /sys/block/mmcblk0/device/date,
>> I'll investigate why this improvement isn't helping you out.
>
> Yeah, sdhci-pxa:
>
> [root@localhost olpc]# cat /sys/block/mmcblk0/device/date
> 10/2010
>
> Want to give me a benchmark script so that we can compare speeds
> directly?
>

One more thing to check - is this an eMMC 4.3+ card? (you're going to
have to plumb something in mmc.c to print it). Sandisk says
improvement going to be seen only on 4.3+ cards. Sandisk releases
different generation cards concurrently, and there is no way to tell
from manfid/oemid/date/hwref/fwrev. Ugh.

I'll send another email (in a bit) with test script and a patch to
enable/disable cmd23 use at runtime so you can get better tests than
across
reboot.

A